Har Gobind Khorana

About Har Gobind Khorana

Har Gobind Khorana also known as Hargobind Khorana (January 9, 1922 – November 9, 2011) was an Indian-American biochemist who shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that helped to show how the order of nucleotides in nucleic acids, which carry the genetic code of the cell, control the cell’s synthesis of proteins. Khorana and Nirenberg were also awarded the Louisa Gross Horwitz Prize from Columbia University in the same year.

He was born in Raipur, British India (today Tehsil Kabirwala Punjab Pakistan) and became a naturalized citizen of the United States in 1966, and subsequently received the National Medal of Science. He served as MIT's Alfred P. Sloan Professor of Biology and Chemistry, Emeritus and was a member of the Board of Scientific Governors at The Scripps Research Institute.

Early life and education

Khorana was born to Hindu parents in Raipur village in West Punjab which is now Pakistan. His father was the village "patwari" (or taxation official). He was home schooled by his father until high school. He earned his B.Sc from Punjab University, Lahore, in 1943, and his M.Sc from Punjab University, Lahore in 1945. In 1945, he began studying at the University of Liverpool. After earning a Ph.D in 1948, he continued his postdoctoral studies in Zürich (1948–1949). Subsequently, he spent two years at Cambridge University. In 1952 he went to the University of British Columbia, Vancouver and in 1960 moved to the University of Wisconsin–Madison. In 1970 Khorana became the Alfred Sloan Professor of Biology and Chemistry at the Massachusetts Institute of Technology where he worked until retiring in 2007.

Khorana married Esther Elizabeth Sibler, of Swiss origin, in 1952. They had three children: Julia Elizabeth (born May 4, 1953), Emily Anne (born October 18, 1954; died 1979), and Dave Roy (born July 26, 1958).

Research work

Ribonucleic acid (RNA) with three repeating units (UCUCUCU → UCU CUC UCU) produced two alternating amino acids. This, combined with the Nirenberg and Leder experiment, showed that UCU codes for Serine and CUC codes for Leucine. RNAs with three repeating units (UACUACUA → UAC UAC UAC, or ACU ACU ACU, or CUA CUA CUA) produced three different strings of amino acids. RNAs with four repeating units including UAG, UAA, or UGA, produced only dipeptides and tripeptides thus revealing that UAG, UAA and UGA are stop codons.

With this, Khorana and his team had established that the mother of all codes, the biological language common to all living organisms, is spelled out in three-letter words: each set of three nucleotides codes for a specific amino acid. Their Nobel lecture was delivered on December 12, 1968. Khorana was the first scientist to chemically synthesize oligonucleotides.

Subsequent research

He extended the above to long DNA polymers using non-aqueous chemistry and assembled these into the first synthetic gene, using polymerase and ligase enzymes that link pieces of DNA together, as well as methods that anticipated the invention of PCR. These custom-designed pieces of artificial genes are widely used in biology labs for sequencing, cloning and engineering new plants and animals, and are integral to the expanding use of DNA analysis to understand gene-based human disease as well as human evolution. Khorana's invention(s) have become automated and commercialized so that anyone now can order a synthetic gene from any of a number of companies. One merely needs to send the genetic sequence to one of the companies to receive an oligonucleotide with the desired sequence.

Since the middle of the 1970s, his lab has studied the biochemistry of bacteriorhodopsin, a membrane protein that converts light energy into chemical energy by creating a proton gradient. Later, his lab went on to study the structurally related visual pigment known as rhodopsin.